dmaengine: virt-dma: Add missing locking

Originally freeing descriptors was split into a locked and an unlocked
part. The locked part in vchan_get_all_descriptors() collected all
descriptors on a separate list_head. This was done to allow iterating
over that new list in vchan_dma_desc_free_list() without a lock held.

This became broken in 13bb26ae8850 ("dmaengine: virt-dma: don't always
free descriptor upon completion"). With this commit
vchan_dma_desc_free_list() no longer exclusively operates on the
separate list, but starts to put descriptors which can be reused back on
&vc->desc_allocated. This list operation should have been locked, but
wasn't.
In the mean time drivers started to call vchan_dma_desc_free_list() with
their lock held so that we now have the situation that
vchan_dma_desc_free_list() is called locked from some drivers and
unlocked from others.
To clean this up we have to do two things:

1. Add missing locking in vchan_dma_desc_free_list()
2. Make sure drivers call vchan_dma_desc_free_list() unlocked

This needs to be done atomically, so in this patch the locking is added
and all drivers are fixed.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Green Wan <green.wan@sifive.com>
Tested-by: Green Wan <green.wan@sifive.com>
Link: https://lore.kernel.org/r/20191216105328.15198-3-s.hauer@pengutronix.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 11 insertions, 11 deletions

diff --git a/drivers/dma/s3c24xx-dma.c b/drivers/dma/s3c24xx-dma.c
index 43da8eeb18ef..1ed5dc1f597c 100644
--- a/drivers/dma/s3c24xx-dma.c
+++ b/drivers/dma/s3c24xx-dma.c
@@ -519,15 +519,6 @@ static void s3c24xx_dma_start_next_txd(struct s3c24xx_dma_chan *s3cchan)
 	s3c24xx_dma_start_next_sg(s3cchan, txd);
 }
 
-static void s3c24xx_dma_free_txd_list(struct s3c24xx_dma_engine *s3cdma,
-				struct s3c24xx_dma_chan *s3cchan)
-{
-	LIST_HEAD(head);
-
-	vchan_get_all_descriptors(&s3cchan->vc, &head);
-	vchan_dma_desc_free_list(&s3cchan->vc, &head);
-}
-
 /*
  * Try to allocate a physical channel.  When successful, assign it to
  * this virtual channel, and initiate the next descriptor.  The
@@ -709,8 +700,9 @@ static int s3c24xx_dma_terminate_all(struct dma_chan *chan)
 {
 	struct s3c24xx_dma_chan *s3cchan = to_s3c24xx_dma_chan(chan);
 	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+	LIST_HEAD(head);
 	unsigned long flags;
-	int ret = 0;
+	int ret;
 
 	spin_lock_irqsave(&s3cchan->vc.lock, flags);
 
@@ -734,7 +726,15 @@ static int s3c24xx_dma_terminate_all(struct dma_chan *chan)
 	}
 
 	/* Dequeue jobs not yet fired as well */
-	s3c24xx_dma_free_txd_list(s3cdma, s3cchan);
+
+	vchan_get_all_descriptors(&s3cchan->vc, &head);
+
+	spin_unlock_irqrestore(&s3cchan->vc.lock, flags);
+
+	vchan_dma_desc_free_list(&s3cchan->vc, &head);
+
+	return 0;
+
 unlock:
 	spin_unlock_irqrestore(&s3cchan->vc.lock, flags);